Alternate-current dynamo



(No Model.)

2 SheetsSheet 1. E. THOMSON. ALTERNATE CURRENT DYNAMO.

Patented 001;. 2, 1888.

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(No Model.) 2 SheetsSheet 2.

E. THOMSON.

ALTERNATE CURRENT DYNAMD.

No. 390,318. Patented Oct. 2, 1888.

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PATENT ALTERNATE=CURRENT DYNAMO.

$PECIFICATION forming part of Letters Patent No. 390,318, dated October 2, 1888.

Application filed July 25, 1857. Serial No. 245,159. (No model.)

To aZZ whom it may concern:

Be it known that I, ELIHU THOMSON, acitizen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented a certain new and use ful AlternatingOnrrent Dynamo, of which the following is a specification.

My invention relates,generally speaking,to dynamo-electric machines or generators, but in many of its features is designed more especially for dynamo-machines organized to deliver alternating electric currents.

The alternating electric currents developed by a machine constructed in accordance with my invention may be employed for any of the usual or desired purposesas,for instance,for supplying currents to mains leading to the primaries of induction-coils whose secondaries connect to translating devices such as incandescent lamps, orfor operating incandescentlamps connected directly in branches between the mains.

The chief object of the invention is to pro duce a simple and easily-controlled machine capable of generating alternating currents of high or of low potential, as may be needed, and which potential may be controlled so as to be raised or lowered or kept constant by manual or other means.

My invention relates to an alternatingcurrent generator having two sets of armaturecoils, both on the same armature structure, one of which is connected directly to the external circuit for supplying alternating currents from the machine, and a commutator placed between the other set of armature-coils and the field-exciting circuit for rectifying the currents supplied from such second set of coils to the field magnet or magnets.

My invention consists in a novel manner of combining the two sets of armature-coils on the same armature structure, one set being the field-maintaining set and the other the working current or linesct, as will be hereinafter set forth.

My invention consists, also, in certain improved combinations and details of construct on, which will be first described in connectron with the accompanying drawings, and then specified in the claims.

In the accompanying drawings, Figure 1 is an end elevatlon of a machine embodying the Fig. 2 1s a side elevation of the invention.

machine and its collecting and commuting arrangements. Fig. 3 is a transverse section of the armature-body. Fig. 4 is an end view of the armature unwound. Fig. 5 is a side view of the armature unwound. Fig. 6 is a diagram showing the mode of application of the coils to the armature-body. Fig. 7 is a diagram showing one'of the line-feeding coils of the armature detached. Fig. 8 is an edgewise view of the coil, Fig. 7. Fig. 9 is a view showing the preferred relations in the position of the field-exciting coil and the line-coils on the armature-core. Fig. 10 is a diagram of the connections of the exciting coil to its commutator and to the fieldmagnet coil. Fig. 11 shows a section of the commutator of the exciting-coil, Fig. 10. Fig. 12 is a diagram showing the relation of the main-circuit or line-feedingcoils to the collectingrings and external circuit.

Referring to Fig. 1, F F indicate a fieldmagnet, formed of a circular or polygonal magnet-frame, from the interior of which fieldmagnet cores project inwardly toward the rotating armature. These field magnet cores terminate at the periphery of a circle a little larger than the diameter of the revolving armature, which latter is mounted on a shaft in the center in any suitable manner, as is well understood in the art. The armature A is wound with an excitingcoil and a set of line-feeding coils, G, for supplying alternating currents to the work. external to the machine. The exciting-coil alone is provided with a commutator, K, for commuting its currents to currents of one direction and passing them out ward into a circuit, 2, 3, 4L, and 5, which circuit includes the commutator-brushes of the commutator, a variable rheostat or resistance, V, of any character, and the field-magnet coils M M M M, &c., which latter are connected either in series or in series multiple, or in multiple are, according to the size of the wire forming the coils. Suitable standards, S, carried by the base-plate of the machine, are provided for supporting the armature shaft and permitting its rapid revolution between the polefaces of the field-magnet cores. The polarity of the faces, as is usual in such machines, is alternating-that is to say, the poles are alternately north and south, proceeding in regular rotation.

In Fig. 2, P indicates a pulley on the driving-shaft X, by which power is applied to rotate the armature-shaft. A indicates the armature complete with coils O C O G on the extev according to the purpose designed.

rior of the armature, corresponding in number and position to the number and position of the field-magnet coils. Bands of wire encircle the armature, as indicated at B B B B, and hold the coils in place thereon.

The coils O O O O, which are shown as six in number in Fig. 3, three only being visible in Fig. 2, are supposed to be connected in one circuit, so that their potentials are added one to the other in producing alternating electric waves, pulsations, though when wound suitably they may be connected partly in series and partly multiple, or entirely in multiple, In any case the terminals of the winding are carried to carefully-insulated rings R R, which form the poles of the machine, and to which are applied, in the manner usual in the art, collecting-brushes, from which brushes conductors are carried to the external circuit.

The excitingcoil E, Figs. 1 and 2, is wound over the body of the armature, and its two terminals are connected to the segments of the commutator K, which segments are insulated from one another. In the casein question the commutator K contains six segments, there being six alternations of current in the coil during a revolution, and every other segment is attached to one terminal of the exciting-coil E, and the remaining alternate segments to the remaining terminal of the exciting-coil E, after the well-known principle. The positions and relations of the windings will be better understood by reference to succeeding figures.

In Fig. 3 the armature is shown in crosssect-ion. The wires 0 O on the exterior are those of the coils which feed the main circuit, and those at EE, passing longitudinally along the armature and over its ends, are those of the excitingcoil for furnishing the current, which, when commuted, energizes the fieldmagnets of the machine. The armature itself is built up, by preference, ofthin sheets or disks of iron piled laterally and encircling the shaft ofthe machine, and carried by or attached to said shaft by any suitable means, as by keying or otherwise.

An end view of the armature-body unwound is seen in Fig. 4. The end plates of thesheetmetal portion constituting the mass of the armature consist of thicker iron plates, preferably ribbed, as shown in both Figs. 4 and 5. These plates are marked 1? 1?, and serve to support the ends of the armature-core. It is preferred, also, to mount upon the ends of the an mature rings G G, of thin metal-such as castiron, brass, or German silverseparated by a small space from the main body of the core and mounted on pins or projecting screws, as shown. \Vooden rings not separated may also suffice. The object of the rings G G is to furnish guides which shall assist in holding the external coils, O O C O, or which assist in providing a seat for the ends of the externallysupport the coils O G, as shown in dot-tedliues' in thesaid figure. They also furnish the means for preventing the said coil from slipping around the armature. The pieces W W are made to fit the interior of the coil as wound. The coils O C are preferably wound on a mold and are flat, almost rectangular, coils, as seen in Figs. 7 and 8. They may be wound flat and afterward bent to fit the exterior of the armature-surface. They are laid on the exterior with the pieces W \V, and the whole is then insulated carefully and well bound with a strong binding of German-silver wire. The coils are thus secured from displacement during revolution either longitudinally or peripherally.

When the exciting coil E is used, as described, it is preferably wound over the armature-body longitudinally, as seen in Fig. 9, and through the space existing in the center of the coils O 0, (one only of which is seen in Fig. 9.) In this case the pieces WV \V and pins corresponding thereto are omitted at the positions in which the coil E passes over the periphery longitudinally.

An important point in conneetionwith the coil E is that it is made of a very few turns of wire, so that the currents generated in it are of quite low potential. I make the turns so few that the potential of the currents of the generating-coil E shall be below that which would sustain an are between metal pieces separated a very small interval, and by this means secure in the commutator used to commute or change the direction of the currents developed in E forsupplying the field a remarkable freedom from sparking, burning, or other irregularities, even though the brushes be displaced from their proper positions for commuting the entire current. This is an important feature in the construction of the machine; otherwise with high potentials-such as surpass forty or fifty volts developed in the exciting-coil E-- considerable difficulty will be found in keeping the commutator K, Fig. 2, adjusted, so as to be free from sparking, and if so adj usted,in preventing sparking on slight changes of position. The position of the exciting-coil E also conduces to the control of the machine, since it possesses a considerable length of inactive wire, besides the active portion which traverses the space in front of the field-poles. This inactive wire is found in the portion of the coil which passes over the ends of the armature,and which may be regarded as dead-wire, but which is useful as possessing a certain amount of self-induction interposed in the exciting-coil. This selfinduction tends to eliminate the irregular actions at the commutator which commutes the currents of said coil.

In practice I find that the exciting-coil, if its potential be kept below thirty or forty volts, answers sufficiently well for the purpose of my invention, the coil 0 O at the same time furnishing a current of one thousand volts,0r whatever the windings and connections should give.

Fig. 10 is a diagram of the connections of the exciting-coil E to the eommntator-seg ments K, and from the brushes of said commutator to the variable resistance V and fieldmagnet coils. The brushes in passing the slots of the commutator (which are preferably filled with an insulating substance and made rather narrow) are not subject to burning produced by spark at the slots of the commutator when the potential of the exciting coil E is below that at which an are or spark can be easily originated between metal surfaces, and the brushes themselves may be displaced consid erably from the exact neutral line of position of the exciting-coil without producing damaging actions at the commutator. I am also enabled by so displacing the brushes forward and backward to regulate the potentials of the currents passing outward from the exciting coil to the rest of its circuit and in some cases to dispense altogether with the variable resistance V, using simply the movement of the brushes around the commutator to effect the same result. The field-magnet coils M M M M in circuit with the commutator K and coil E require, of course, to be wound with coarse wire of such low resistance that a sufiicient-lystrong exciting-current may flow with the low electro-molive force developed by the coil E.

The preferred construction of the commutator K of the machine is to make its segments with feetf projecting radially inward and tapering or spreading at the end, as shown in Fig. 11, so that they may be grasped between sleeves in the form of hollow cones, as atYY, with interposed insulating material between the feetf and the hollow conical surfaces. In this manner I am able to secure a large diameter in the commutator, such as is required when the commutator contains a number of alternating positive and negative segments, and at the same time,at a very small expense of ma terials, to hold the parts in position and insulate them from one another. The form of a single segment is shown at K.

In Fig. 12 the coils GO, &c., are shown connected in series and to the rings R R, from which, by suitable brushes or collectors, DD, connection is made to the external circuit of the machine.

During the operation of the machine adjustments of the excitation of the field-magnets may readily be made, so as to secure a given potential at the armature-terminals, which are connected to the rings RR, by vary ing the amount of current generated in the excitingcoil E, either by shifting its commutator-brushes or by introducing more or less of the variable resistance V into the circuit of the exciting-coil and the magnet-coils.

lVhat I claim as my invention is--- 1. In a dynamo-electric machine, an armature provided with two coils, as described,one applied to the exterior or periphery thereof and furnishing the working or line current, and the other being wound longitudinally over the same armature structure and supplying the exciting-current for said machine.

2. The combination, for an alternatingcurrent dynamo, of a high-tension alternating current coil connected directly with the work, a low-tension coil applied to the same armature, a field-magnet coil, and an intermediate adjustable commutator between said low-tension coil and field-magnet coil for varying the action of the machine.

3. In a dynamo armature, line or work supplying coils applied to the outside or periphery of the armature, as described, so as to have small self-induction,in combination with fieldmaintaining coils applied to the same armature so as to inclose the armature-body.

4. The combinatiomwith flatarmature-coils applied to the periphery of the armature, of independent coils wound over the armaturebody and in the spaces in the center of the first-named coils.

5. In a dynamo-machine, an armaturecore body of disks of iron piled laterally and se cured so as to rotate with shaft, and having heavier end plates for same, in combination with coil supporting or seating rings of wood or metal at the ends ofarmature, as described.

6. The combination, with the armature-core body, of the projecting pins, and the pieces of insulating material strung on said pins and adapted to fit the interior of the coils lying upon the surface of the armature.

7. The combination, with the multipolar field-magnet and a series of armature-coils corresponding in number thereto, of a single independent coil wound on the same armature and connected at its terminals to a commutator the number of whose segments correspond to the field-magnet poles.

S. The combination, in a dynamo-electric machine, of higlrtension armature-coils connected directly with the work, a lowtension armature-coil revolving in the same magnetic field, a field-magnet coil, and an intermediate current adjusting commutator between the low-tension coil and the fieldunagnet coil, whereby the output of the machine may be varied.

Signed at Lynn, in the county of Essex and State of Massachusetts, this 9th day of July, A. D. 1887.

ELIHU THOMSON.

\Vitnesses:

Orrs K. STUART, J. W. GIBBQNEY.

ICC 

